Hair straightener



FIG. 1 is a perspective view of a hair straightener showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a left side perspective view thereof;

FIG. 5 is a right side perspective view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

In the drawings the broken lines show portions of the article which form no part of the claimed design. 

CLAIM The ornamental design for a hair straightener, as shown and described. 